7-Bromoisatin: Properties, Handling & Lab Use Guidelines

7-Bromoisatin is a halogenated isatin derivative widely employed as a versatile heterocyclic building block in medicinal chemistry and synthetic organic chemistry research.

Chemical Name

7-Bromoisatin (7-Bromo-1H-indole-2,3-dione)

CAS Number

20780-72-7

Molecular Formula

C₈H₄BrNO₂

Molecular Weight

226.03 g/mol

Appearance

Orange to red crystalline solid

Aladdin SKU

B153061

Overview and Chemical Properties

7-Bromoisatin (7-Bromo-1H-indole-2,3-dione, CAS 20780-72-7) is a halogenated derivative of isatin, the parent bicyclic compound comprising a benzene ring fused to a pyrrolidine-2,3-dione ring. The introduction of a bromine substituent at the 7-position of the indole ring system markedly alters the electronic character of the molecule, increasing electrophilicity at the carbonyl centres and facilitating cross-coupling reactions at the C–Br bond.

Key physicochemical characteristics include an orange-to-red crystalline appearance, a molecular weight of 226.03 g/mol, and the molecular formula C₈H₄BrNO₂. The compound is sparingly soluble in water but dissolves readily in polar aprotic solvents such as DMSO, DMF, and acetonitrile, as well as in common organic solvents including ethanol, acetone, and ethyl acetate.

The reactive 3-carbonyl group and the N–H moiety make 7-Bromoisatin amenable to condensation, cyclisation, and nucleophilic addition reactions, while the aryl bromide enables palladium-catalysed cross-coupling transformations (e.g., Suzuki, Buchwald–Hartwig). These combined reactive handles render the compound exceptionally valuable as a bifunctional building block.

Safe Handling and Storage Protocol

Personal Protective Equipment (PPE): Always wear nitrile gloves, a laboratory coat, and safety spectacles when handling 7-Bromoisatin. If powder handling generates dust, use a half-face respirator rated for organic dusts or work inside a ventilated fume hood. The compound contains an aryl bromide and a diketone functionality; avoid inhalation of dust or vapours and prevent skin and eye contact.

Storage Conditions: Store 7-Bromoisatin in a tightly sealed container under cool, dry, and dark conditions, ideally at 2–8 °C or as specified on the product certificate of analysis. Protect from moisture and light, as prolonged exposure may cause discolouration or partial degradation. Keep away from strong oxidising agents, strong bases, and reducing agents.

Waste Disposal: Dispose of waste material in accordance with applicable local, regional, and national regulations. Do not discharge into drains or water courses. Halogenated organic waste should be collected separately and processed by a licensed chemical waste contractor.

First Aid Measures: In case of skin contact, wash thoroughly with soap and water for at least 15 minutes. For eye contact, irrigate immediately with copious water for at least 15 minutes and seek medical attention. If inhaled, move the affected person to fresh air and seek medical advice if symptoms persist.

Synthetic Applications and Reaction Protocols

General Considerations: 7-Bromoisatin is a multifunctional building block exploited across several reaction classes. Researchers should dry solvents appropriately and use inert-atmosphere (N₂ or Ar) techniques for moisture- or oxygen-sensitive transformations.

Condensation Reactions: The reactive C-3 carbonyl of 7-Bromoisatin readily undergoes Knoevenagel-type condensations with active methylene compounds (e.g., malononitrile, rhodanine) under mild base catalysis (e.g., ammonium acetate or piperidine in ethanol at reflux) to furnish arylidene derivatives useful as fluorescent probes or bioactive scaffolds.

Palladium-Catalysed Cross-Coupling: The aryl C–Br bond participates in Suzuki–Miyaura coupling with arylboronic acids using Pd(PPh₃)₄ or Pd(dppf)Cl₂ as catalyst, K₂CO₃ as base, and DMF/H₂O as solvent at 80–100 °C. Buchwald–Hartwig amination can install nitrogen-containing substituents at the 7-position, expanding structural diversity.

Cyclisation to Spirooxindoles and Fused Heterocycles: 7-Bromoisatin participates in 1,3-dipolar cycloadditions and multicomponent reactions (e.g., with isocyanides and amino acids in Ugi-type protocols) to construct spirooxindole scaffolds with pharmacological relevance.

Typical Reaction Setup: Weigh the required quantity of 7-Bromoisatin in a fume hood, transfer to a dry round-bottom flask, dissolve in the chosen solvent, add reagents sequentially under stirring, and apply the specified temperature. Monitor reaction progress by TLC or HPLC. Work up and purify by column chromatography (silica gel, ethyl acetate/hexane gradient) or recrystallisation.

Quality Control and Analytical Characterisation

Upon receipt, visually inspect the product for the expected orange-to-red crystalline appearance. Cross-check the lot number against the Certificate of Analysis (CoA) provided by Aladdin Scientific. Key analytical parameters to verify include:

• Purity: Confirm by HPLC (≥97% or as stated on the CoA). A single dominant peak in the UV-active region (monitored at 254 or 280 nm) is expected for a high-purity batch.
• Identity: ¹H NMR in DMSO-d₆ should show characteristic signals including the N–H singlet (broad, ~10–11 ppm) and aromatic protons in the 7.0–7.8 ppm region. ¹³C NMR confirms the two carbonyl carbons (~158 and ~182 ppm).
• Mass Spectrometry: ESI-MS or EI-MS should show a molecular ion cluster at m/z 225/227 (⁷⁹Br/⁸¹Br isotope pattern, 1:1 ratio) consistent with C₈H₄BrNO₂.
• Melting Point: Compare the observed melting point with the literature or CoA value as an additional identity check.

If any parameter falls outside specification, quarantine the lot and contact Aladdin Scientific customer support for guidance before use.

Frequently asked questions

What solvents are recommended for dissolving 7-Bromoisatin?

7-Bromoisatin dissolves readily in polar aprotic solvents such as DMSO, DMF, and acetonitrile, as well as in ethanol, acetone, and ethyl acetate. It is sparingly soluble in water. For stock solutions intended for biological assays, DMSO is generally preferred; ensure the final DMSO concentration in assay media does not exceed tolerated limits (typically ≤0.1–1%).

How should 7-Bromoisatin be stored to maintain its stability?

Store 7-Bromoisatin in a tightly sealed container at 2–8 °C, away from light and moisture. Prolonged exposure to air, humidity, or elevated temperatures may cause discolouration or degradation. Always return the container to appropriate storage conditions promptly after use and check purity by HPLC if the compound has been stored for an extended period.

Can 7-Bromoisatin be used in palladium-catalysed cross-coupling reactions?

Yes. The aryl C–Br bond in 7-Bromoisatin is compatible with standard palladium-catalysed cross-coupling methodologies, including Suzuki–Miyaura coupling with boronic acids and Buchwald–Hartwig amination. Typical conditions involve a Pd(0) or Pd(II) precatalyst, an appropriate phosphine ligand, a carbonate or phosphate base, and a polar solvent such as DMF or dioxane at elevated temperature (80–100 °C) under inert atmosphere.

What safety precautions are required when handling 7-Bromoisatin?

Wear nitrile gloves, a laboratory coat, and safety spectacles at all times. Handle powders inside a fume hood to minimise dust inhalation. Avoid contact with skin, eyes, and mucous membranes. In the event of skin contact, wash with soap and water for at least 15 minutes; for eye exposure, irrigate with water for at least 15 minutes and seek medical attention. Dispose of waste as halogenated organic waste in accordance with local regulations.

References

1. Aladdin Scientific. 7-Bromoisatin, Product Page, SKU B153061. Certificate of Analysis available upon request.
2. Matsuura, A. et al. Isatin and its derivatives: a mini-review of biological activities. Mini-Reviews in Medicinal Chemistry (general reference — specific article details need verification).
3. Clayden, J.; Greeves, N.; Warren, S. Organic Chemistry, 2nd ed.; Oxford University Press: Oxford, 2012. (General reference for cross-coupling reaction protocols.)

Products are supplied for research and development use only. Not for use in humans, animals, diagnosis, or therapy.